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Food production by C3 and C4s

Plants!

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Postby 2810712 » Thu Apr 07, 2005 6:16 am

One more point, in my book they have told that this happens at very high temp and intensity, so in such conditions i doubt if the enzymes are functional. Enzymes of C4 if , be functional at such conditions, can explain this behavior.
Also,The closing of the stomas is a cell response to the lack of water, as in high temperatures a great deal of water is lost through transpiration. C3 plants aren't addapted to reduce transpiration. A side effect is excess O2 - Andrew
Do u mean C4s are adapted for more temp ? ? ? But in such an intense environment do they really be able to keep the stomas open ? ? ? I'm doubtful.

I searched in many books but no one could make it clearer.

Hmm,,,

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Postby thank.darwin » Thu Apr 07, 2005 11:29 pm

C4 plants open their stomas at night... the temp. is much lower and they can take in CO2 without losing water... their stomas are closed during the day... when they collect CO2 at night they store it and are able to use it during the day. Does that help?

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Postby Poison » Fri Apr 08, 2005 12:12 am

someone correct me if I'm wrong, (thinking that It's 3 am here, my brain may not be working properly. :lol: ), CAM plants take CO2 during night not C4.
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Postby 2810712 » Fri Apr 08, 2005 10:57 am

I'm totally awake CAMs open stomas in night, yeah poison.
[ My senior friends also, couldnot tell me why C4s can and C3s can't]
I'm totally awake ... I think so...

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Postby dr.pnj » Thu Apr 14, 2005 2:24 pm

hi
solarization is the destruction of chlorophyll molecules
it is prevented by carotenoids
maybe c3plants do not have the necessary amount of carotenoids and hence due to solarization their chl molecules get destroyed or subdued
c4 plants show kranz anatomy
they have grana with and without cloroplast so may be this helpsin the continuation of photosynthesis even under extrene conditions
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Postby 2810712 » Fri Apr 15, 2005 4:40 am

Probably that's it.
See in C4s photosynthesis' main process occurs in bundle sheath and probably the ammount of light reaching there in extreme conditions can run photosynthesis but cannot damage its machinary... because photosynthesis doesn't require much light ...
i'm just guessing ...

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Postby thank.darwin » Fri Apr 15, 2005 11:19 pm

Poison wrote:someone correct me if I'm wrong, (thinking that It's 3 am here, my brain may not be working properly. :lol: ), CAM plants take CO2 during night not C4.


Sorry about that :oops: ... CAM plants take in CO2 at night :lol:
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Postby MrMistery » Sat Apr 16, 2005 9:06 am

C3 and C4 plants have the same amount of carethoid pigments(maybe not exatcly the same, but antway it is not caused by this). I checked my books and it sais that C4 are adapted to less water, but not as much as cam plants. The answer you are looking for is the fact that the enzyme in c3 plants(RUBISCO) has an affinety for O2 as well as CO2- the C2 cycle. Thus, a C3 plant has to keep it's stomas open longer in order to produce the same amount of glucose. The enzyme present in c4 plants(fosfoenolpiruvate carboxylase) does not have this affinity. Now the c4 cylce is extremely complicated- all you need to know is that c4 plants produce glucose 6 times faster and 40% more efficient then C3 plants. CAM plants produce even less eficient than c3 plants but that is a different story
Hope this helpes
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Postby 2810712 » Tue Apr 19, 2005 6:02 am

See, what i'm trying to ask is why do c3s cannot carry out photosysnthesis at higher temp and intensities of light and c4s can .



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Postby MrMistery » Thu Apr 28, 2005 7:35 pm

Sorry, i only saw your question now. The fundamental enzyme of photosynthesis is Rubisco, but i am sure you knew that. As you know this enzyme can bind O2 as well as CO2. This problem gets bigger in high temperatures, as past 30 degrees celcius the oxygenic function tends to dominate the carboxylic function. when this exceeds 50% the plant is losing more than it is gaining. C3 plants have this problem. C4 plants have solved by isolating the Rubisco enzyme from O2, so they can do photosynthesis no matter what temp it is outside.
Of course, this is a squetch... no details included. If you want details let me know, i will be happy to give you some.
I think this is enough for your curiosity though :D :D
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Postby 2810712 » Fri Apr 29, 2005 11:26 am

Thanks, this was photorespiration.

I think this is not imp for me at this stage to understand every detail, but i knew photorespiration and the problem was not that - the statement in the book says that C3 s can't photosynthesize in EXTREME conditions of temp and intensity of light . So, i don't know how do they author defines 'Extreme' . This can only solve my problem. So, i'm now after the author. :wink:

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